There is currently a trend by passenger vehicle body manufacturers to design window assemblies so that in the up or closed position of the glass, all or a substantial portion of the glass above the belt line, especially the upper edge portion, is flush or essentially flush with the outer surface of the vehicle. The main purpose of this so-called flush-glass arrangement is to reduce frictional wind drag during operation of the vehicle, it having been found that the more conventional recessed position of the glass relative to the exterior of the vehicle produces substantial wind drag and consequent wind noise and absorption of energy. A fuller discussion of the advantages of a flush-glass arrangement in passenger vehicles and examples of such assemblies can be found in, for example, U.S. Pat. No. 4,240,227.
A flush-glass arrangement inherently raises the question of how to achieve an efficient seal between the vehicle body and the top and side edges of the glass in the closed position, because the requirement of a flush arrangement inherently excludes the use of fixed side channels directly engaging the glass. Window assemblies of the kind described in the above-identified patent employ fixed polymeric sealing strips which are carried by the frame forming the window opening. The side edges of the glass (i.e. the edges facing in the plane of the glass) and the adjacent inner surfaces of the glass are in full-time sealing contact with their respective sealing strips, while the adjacent outer surfaces of the glass are free of contact with the strips in order to achieve the flush arrangement. In such an assembly it is necessary, in order to form a tight seal, to have the glass in tight engagement with the sealing strips. As a result the seal is a sliding seal during movement of the glass with consequent wear on the seal during vertical movement of the glass. In addition, there is substantial friction, and hence substantial resistance to movement of the glass, especially as the glass approaches its full closed position, because of the large area of contact between the glass and the sealing strips.
The principal object of the present invention is to provide a flush-glass window assembly for automobile vehicles in which a sliding seal is avoided during vertical movement of the window glass and in which a tight compression seal is effected at the end of the closing movement of the glass by movement of the glass toward and into sealing contact with the sealing strips. This arrangement has several advantages. First, the absence of any significant frictional contact between the side edges of the glass and the respective sealing strips during vertical movement of the glass reduces the effort required to move the glass. Second, a compression seal is recognized in the sealing art as a more efficient seal than a sliding seal and hence the use of a compression seal for the glass is preferable to a sliding seal. Third, use of a compression seal rather than a sliding seal avoids abrasive or frictional wear on the sealing strip.
In the preferred construction according to the present invention movement of the glass into compression with the sealing strips is effected by cooperation between at least one fixed guide track spaced from and extending generally parallel to one of the vertical side edges of the glass and a guide member such as a pin or roller projecting from and secured directly to the glass near its upper edge and riding in the track. The upper end portion of the track angles inwardly toward the interior of the vehicle with the result that the guide member and hence the upper edge portion of the glass move inwardly as the glass approaches its full up position. Fixed sealing strips to be engaged by the side and upper edges of the glass are carried by the window frame of the vehicle body. The side sealing strips face outwardly and are located relative to the glass such that there is little or no contact between them and the glass except when the glass moves inwardly as it approaches its full up position. Thus there is no frictional resistance to vertical movement of the glass and no frictional wear on the side strip, yet an efficient compression seal is formed with the glass moves inwardly when arriving at its up position. The sealing strip for the upper edge of the glass also includes an outwardly facing sealing surface which forms a compression seal when the glass moves inwardly.
The above-described movement of the glass is actually a tilting movement about the lower edge portion of the glass. Tilting will normally be accommodated by slight bending of the components of the raising and lowering mechanism and/or bending of the connection between the mechanism and the lower edge of the glass and/or by flexing of the beltline strip to allow movement of the glass. The scope of the present invention extends, however, to arrangements in which the entire glass moves horizontally inward, with little or no tilting or bending. This can be accomplished by providing a second, lower guide track, analogous to the track described above, for guiding the lower edge portion of the glass. In either case no specially designed raising and lowering mechanism is required.
Inward tilting and/or inward horizontal movement of automotive window glass as the glass approaches its full up position is not new per se. German Auslegeschrift No. 1060286 discloses an automotive window assembly of the recessed-glass type having a window glass which is tilted inwardly as it approaches its full up position in order to counteract the exterior vacuum during operation of the vehicle. The tilting movement is effected by guide rails disposed within the body of the door in which the window is mounted, the guide rails forming part of the raising and lowering mechanism. German Auslegeschrift No. 2027241 discloses another automotive window assembly of the recessed-pane type in which a frameless glass pane is tilted inwardly during the last portion of its upward movement. By frameless is meant that there is no frame attached to and movable with the glass. The assembly has special utility in vehicles driven at high speed wherein there is a strong tendency for the glass to be pushed outwardly at high car speed due to excessive pressure build-up inside the car.
German Offenlegungsschrift No. 2435766 discloses an automotive window assembly in which the glass pane is moved outwardly as it reaches its full up position in order to become flush with the exterior of the vehicle body.
The use of a guide track and a guide member attached directly to the glass in an automotive flush-glass window assembly is known. An example of such an assembly appears in the aforesaid U.S. Pat. No. 4,240,227.
U.S. Pat. Nos. 2,317,312 and 3,538,642 disclose horizontally slidable household window sash assemblies having guide channels which cause the movable sash to move outwardly at the end of a closing movement so as to bring the sash into compression against the weatherstrip.
U.S. Pat. No. 3,423,876 discloses an automobile window assembly in which the glass moves upwardly and outwardly in order to "open" the window and moves downwardly and inwardly to a closed position.